Retinitis pigmentosa (RP) is a group of degenerative disorders of the retina that leads to serious visual disability or total blindness in its victims. To increase our understanding of these diseases, we propose a series of investigations in patients with RP using broad field imaging fundus reflectometry (IFR). IFR, an improved version of a traditional technique, permits noninvasive objective measurement of visual pigments in rod and cone photoreceptors across wide areas of retina. With IFR, new subtypes of autosomal dominantly inherited RP have recently been identified. These "photochemical subtypes" are likely to differ in pathogenesis and eventually in treatment. Our intent is to use IFR to study the largest and least well understood group of RP patients, simplex or isolate RP. First, we will determine whether there are photochemical differences among patients in this group. Second, in a subset of these patients who have no detectable electroretinogram, IFR will be used to measure change in visual pigment levels in different retinal regions over a two year period. Natural history data will thus be obtained in RP patients in whom there would otherwise be no objective means to monitor the progress of their disease or the effect of treatment.